Spatial coherence properties of surface plasmon investigated by Young's slit experiment.

In this Letter, we present an original method to extract the optical properties of surface plasmon polaritons (SPPs) on silver surfaces. A two Young's slit experiment combined with a leakage radiation microscope has been built. By correlating both imagery and coherence measurements on the same area, we are able to address the evolution of the SPP spatial coherence along its propagation. The proposed method could also be useful to explore the properties of complex plasmonic systems.

Coherent emission from a disordered organic semiconductor induced by strong coupling with surface plasmons.

In this Letter, we show that the strong coupling between a disordered set of molecular emitters and surface plasmons leads to the formation of spatially coherent hybrid states extended on macroscopic distances. Young-type interferometric experiments performed on a system of J-aggregated dyes spread on a silver layer evidence the coherent emission from different molecular emitters separated by several microns. The coherence is absent in systems in the weak-coupling regime demonstrating the key role of the hybridization of the molecules with the plasmon.